Polarity and Continuity are terminologies that are associated with electrical and electronic components, and questions always arise whether resistors have polarity and continuity. This article shall delve deeper into these two concepts and see if resistors have polarity or continuity. 

What is polarity?

Polarity is a term that is used in many branches of science and technology such as electricity, magnetism, and chemistry. It is described as ; “a state or condition of an atom or molecule that exhibits opposite properties or powers in opposite parts or directions.” For example, a magnet is known for having North and South poles. Here magnetic polarity refers to the orientation of these poles in space. 

But, the polarity we are concerned about in this article pertains to electricity. So what exactly is electric polarity? 

Electric Polarity

Voltage can be defined as an Electromotive Force (EMF) between two points. When we are talking about these two points, we are looking at which point has more electrons than the other. The point that has more electrons is the Negative Pole, making the other point a Positive Pole.

Now when a conductor (such as wire) is used to close the path between the two poles, electrons flow from the negative pole to the positive pole (this flow of electrons is known as current). An example of this is a battery which has negative and positive terminals (or poles). Connecting a wire across the two terminals will cause electrons to flow from the negative terminal to the positive.

Components and polarity

So how does polarity relate to electrical and electronic components? They can be divided into two categories when it comes to polarity;

• Polarised or,
• Non-Polarized

Non-Polarised components do not have any polarity. These components can be placed in a circuit in any orientation without altering their functionality. 

Polarised components on the other hand have polarity. This means they have been constructed in a way where one of their terminals has more electrons than the other. They will have one negative and positive terminal. Therefore they will have to be placed in a circuit in the right orientation (their terminals must match the terminals of the voltage source). A common example of a polarised component is a battery. 

Do resistors have polarity?

No, resistors do not have polarity. They do not have positive or negative terminals which means that they can be placed in any orientation when connecting them up in a circuit. The main job of a resistor is to provide resistance to limit the flow of current. They are designed uniformly so that one terminal will not have more electrons than the other. The result being no matter what their orientation, they will still provide the same resistance.

A common analogy to better understand this is a road with bumps. Just like a resistor, the bumps on the road provide resistance when you drive past them. And just like a resistor, it doesn’t matter which way you are travelling, the bumps on the road are still going to provide the same resistance.

What is continuity?

Continuity is a term used in many aspects of life. It is defined as “the unbroken and consistent existence or operation of something over time.” When it comes to electricity the concept remains the same. Electric continuity refers to the presence of a continuous unbroken path for current to flow. 

Imagine we had a closed circuit with a battery source as seen below. 

The image below highlights two scenarios. Scenario A has a  wire that connects the positive terminal to the negative terminal without any physical breaks in it. Therefore it is said to have continuity as current can flow from the negative terminal to the positive terminal without interruption.

In Scenario B we see there is a physical break in the wire. In this instance current cannot flow from the negative terminal of the battery to the positive as there is no ‘continuous path’. Therefore the wire has no continuity.

Do resistors have continuity?

Yes, resistors do have continuity. Even though they might limit the flow of electrons (by providing a resistance), they still provide a continuous path for the electrons to through. 

Testing the continuity of a resistor using a multimeter   

Knowing if a wire or component has continuity or not is essential when it comes to circuit analysis. Wires and components are insulated to protect us from potential harm. But, if damage occurs it might be hard to detect it by just looking at it as the insulation might obstruct the damage. 

A multimeter is an electrical/electronic measurement tool used to measure things like voltage, current, resistance, etc. It also has the ability to test continuity. The multimeter has two probes that get  placed on two ends of wire for example. It then sends a current from one probe to the other (via the wire). If there is a break in the wire the multimeter will remain silent indicating no continuity. But, if the other probe receives the signal, this indicates that there is no break in the wire (hence it has continuity), and the multimeter will inform you with an audible beep. 

However, when testing the continuity of resistors, some issues arise. The multimeter’s continuity function works only below a certain threshold value of resistance. Anything above this threshold and the multimeter won’t be able to detect if there is continuity or not. So, even if a resistor with a high value of resistance has continuity, the multimeter might not pick it up.

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It shares the same functionality as the original diode (which is to allow current to only flow in one direction), but with an added ability of allowing a large current to flow at a critical voltage.

Zener diodes are used in applications which include voltage regulation, being used as reference elements, surge suppressors, switching applications, to name a few. 

But, do zener diodes have resistance and polarity? Yes the zener diode has resistance known as Rz, as well as having polarity (which means it can only be placed in a certain orientation in a circuit).

This article shall take a closer look at the resistance, and polarity of zener diodes. 

What is a zener diode?

Zener diodes are designed to allow current to flow in the reverse direction when a certain voltage is reached. 

It is a semiconducting device which consists of a heavily doped P-N Junction.

The advantage of the zener diode compared to the original diode is that it is able to provide a stable reference voltage. The voltage across the zener diode remains constant over a wide range of voltages.

This is the reason they are used regularly in voltage regulation applications. 

What is resistance?

Let’s take a quick look at resistance which will help you understand how a zener diode has resistance. 

However, if you are well versed with resistance, you can skip this section. 

So what exactly is resistance? 

Resistance can be seen as a force that opposes the flow of current. The more resistance the less current can flow, and decreasing the resistance allows more current to flow. 

It is measured in Ohms with the symbol of Ω.

You might be familiar with the component known as a Resistor. This component has the sole function of limiting the flow of current. 

Resistors have a known resistance.

However, every single material will have the ability to resist the flow of current. Some have higher resistance and they usually fall under the Insulator category. Materials like glass, paper, rubber, etc.

In the other category we have Conductors which are metals such as Gold, Silver, Copper, etc. These materials offer less opposition to the flow of current.

However, all metals do not have the same resistance, they vary from one to the next. 

For example, copper has lower resistivity (offers less opposition to the flow of current) compared to aluminum and is why it is commonly used as a conductor in electrical and electronic circuits and components. 

Resistance  and resistivity of materials

As mentioned above, all materials have some sort of resistance.

The resistance of a material is given by its resistivity and is the physical property of the material. Resistivity and resistance are two separate entities and should not be confused as for one another. 

Resistivity is defined as the amount of resistance a material has per unit length for a cross-section. The unit for resistivity is ohm-meter.

Whereas, resistance is the overall value of the material.

Do zener diodes have resistance?

So does a zener diode have resistance?

Yes, zener diodes have a resistance which is known as the zener diode’s internal resistance and can be viewed like a series resistor.

Where RZ is the zener diode’s resistance.

But how do they have resistance?

In a perfect world the zener would have no resistance, but, unfortunately, we do not live in a perfect world and it does have some internal resistance.

This comes down to what we have learnt about materials and how every single material has some sort of resistance (whether it be real small, or real high).

The construction of the zener diode will mostly be metal based, therefore it is going to have resistance, however, it will not be very high due to the zener diode’s physical size as well as which conductors are used to construct them (ones with lower resistivity).  

What effects does this internal resistance have on the zener diode?

This resistance can be unwanted.

We stated earlier that the voltage across the zener diode is stable and does not vary. However, this is not entirely true.

The internal resistance of the zener diode is to blame here. 

As current through the diode (Iz) rises, the voltage (Vz) rises as well because of the resistance and what we know of the Ohm’s Law.

Current and resistance share a directly proportional relationship with voltage. As the current rises so too does the voltage due to the small resistance.

If the resistance was zero, a change in current would not affect the voltage as the total would be equal to zero.

Therefore the lower resistance of the zener diode the better. 

What is the typical value of zener diode resistance?

There isn’t one specific company that manufactures all zener diodes. There are many companies who are involved in the process.

Therefore, zener diodes across companies will vary in many aspects such as what materials they use, as well as production methods. 

Also, zener diodes come in a range of sizes.

So there isn’t one typical value of resistance across all zener diodes.

Zener diodes, like other components, come with a datasheet (that is provided by the manufacturer). Datasheets include important information about components. 

The resistance Rz of the zener diode is one its important parameters and will be included in the datasheet. This value included is the maximum value of resistance. 

What is polarity?

Next let’s take a look at whether a zener diode has Polarity.

So, what exactly is polarity?

Polarity is a term used across different disciplines such as chemistry, magnetism and electricity. 

It is described as ; “a state or condition of an atom or molecule that exhibits opposite properties or powers in opposite parts or directions.”

For example, a magnet is known for having North and South poles. Here magnetic polarity refers to the orientation of these poles in space. 

Electric polarity

But, when it comes to zener diodes, we are more concerned about electric polarity.

Voltage can be defined as an Electromotive Force (EMF) between two points. When we are talking about these two points, we are looking at which point has more electrons than the other.

The point that has more electrons is the Negative Pole, making the other point a Positive Pole. 

Now when a conductor (such as wire) is used to close the path between the two poles, electrons flow from the negative pole to the positive pole (this flow of electrons is known as current).

An example of this is a battery which has negative and positive terminals (or poles). 

Connecting a wire across the two terminals will cause electrons to flow from the negative terminal to the positive.

Components and polarity

So how does polarity pertain to electrical and electronic components?

They can be divided into two categories when it comes to polarity;

• Polarized or,
• Non-Polarized

Non-Polarised components do not have any polarity. These components can be placed in a circuit in any orientation without altering their functionality.

A resistor is an example of a non-polarized component. 

Polarized components on the other hand have polarity. This means they have been constructed in a way where one of their terminals has more electrons than the other. 

They will have one negative and positive terminal. Therefore they will have to be placed in a circuit in the right orientation (their terminals must match the terminals of the voltage source). 

A common example of a polarized component is a battery. 

Do zener diodes have polarity?

So, do zener diodes have polarity?

Yes, zener diodes have polarity and are classed as polarized components. One of its terminals will be negative, while the other will be positive. 

The two terminals of the zener diode are known as the Anode and Cathode, where the anode is the positive terminal, and the cathode is negative.

When biased in the forward direction, the cathode becomes negatively charged compared to the anode.

How do you identify the positive and negative terminal of a zener diode?

Since the zener diode has polarity, you will need to place it in the right orientation in order for it to function properly.

But how do you identify which is the positive and negative terminal? 

Even if you picked up two diodes which were manufactured from separate companies, they would still use the same convention to identify the positive and negative terminal. 

All diodes have a black band that is painted on the negative side of the diode (as seen in the image below). Or if the diode is black, it will have a silver or white band. 

So, make sure that the side with the black band is connected to the negative rail of your circuit.

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Each component will have a specific purpose in the circuit it is placed within.

One of these components is the Inductor.

An important characteristic of components is whether they have electrical polarity, which determines whether they have negative and positive terminals (this shall be discussed in more detail later in the article).

So, do inductors have polarity? No, inductors do not have polarity and can be placed in any orientation in a circuit. 

However, the orientation that an inductor is placed in a circuit can affect electrical properties such as its inductance which will be discussed in more detail in this article. 

Deeper look at inductors and polarity

To understand the question at hand, we will first need to take a step back and learn a bit more about Inductors and Polarity individually. 

What is an Inductor?

Let’s start our journey with the Inductor. 

As mentioned at the start, the Inductor is a crucial component utilised for many different applications. It is also often referred to as a coil, choke, or reactor. 

But, what exactly is an Inductor? 

An inductor is a two terminal passive component which has the ability to store energy in the form of a magnetic field when current flows through it.

The main purpose of an Inductor is to oppose any sudden changes in current. 

They slow down current spikes and surges by storing this extra energy in their magnetic field and then slowly releasing it back into the circuit.

Its ability to resist this change can be shown by its Inductance which is the ratio of voltage and current change within the inductor. 

Inductance is given in the unit of Henry (H).

Construction and working principle of an Inductor

If you were to look at a circuit schematic which had an inductor, you would see a symbol as seen below. 

The construction of a basic Inductor involves a wire that is coiled around a core material. 

This core material can vary depending on the needs of the application and can include either magnetic iron or ferrite core (amongst the most common).

An insulated copper wire is the choice of material for the wire wrapped around the core. 

There are many variables that can alter the inductance of an inductor which include; number of turns (of the wire), spacing between turns, number of layers of turns, material of core, magnetic permeability of core material, size, and shape. 

So how does an inductor work?

As current starts to pass through the inductor, a magnetic field is generated. The relationship between current and the strength of the magnetic field are directly proportional.

So, an increase in current will see an increase in the strength of the magnetic field. 

What is polarity

If you have ever had to replace batteries (whatever the device may be), you know there is a certain orientation that the batteries need to be placed.

Batteries are marked with two symbols; a plus sign (+), and a minus sign (-).

The plus sign (+) represents the positive terminal of the battery, whereas the minus sign represents the negative terminal. 

These are the two main poles in a circuit which are known as polarity.

Polarity lets us know the electric potential at the ends of a circuit or component and lets us know the direction of the flow of electrons. 

The positive pole is commonly associated with the colour red, while the negative pole is black.   

What gives a component polarity  

Polarity happens when one point in a circuit, or component has more electrons than the other (making it negative), and making the other side positive.

This imbalance of electrons tends to occur in circuits/components that are asymmetrical (not symmetrical).

Symmetrical components such as a resistor are non-polarised as there is no imbalance of electrons at either of its terminals.

Components such as an electrolytic capacitor which has an asymmetrical construction, has one side more negative (cathode), than the other (anode) making it polarised. 

Do inductors have polarity?  

Ok, now that we have learned a bit about inductors and polarity let’s take a look at the question at hand. 

Does an inductor have polarity? 

No, due to the symmetrical construction of an inductor, it does not have polarity. 

As we just saw, symmetrical components are non-polarised. If you look back at the construction of the inductor, you can see that it is essentially a wire which has been coiled.

Wires can be placed in any orientation in a circuit as they do not have polarity. This holds true for an inductor as well.  

The coiling of the wire will be the same no matter what orientation the inductor is placed in the circuit. 

But, this is not the end of the story. The orientation that an inductor is placed in a circuit can have an affect on its overall inductance. 

Does the orientation of the inductor matter?

In an ideal world inductors would be perfectly symmetrical. Unfortunately we do not live in an ideal world. In reality inductors are going to be a little bit of of shape and have some defects 

While reversing the inductor does not affect its windings, other physical aspects can change depending on orientation which could include things like the mechanical shape, drum, rod, core, etc

The asymmetry of these factors could affect certain electrical properties (such as inductance) of the inductor. 

But, reversing the orientation of the inductor does not affect the overall functionality as inductors do not have polarity. 

No polarity, but direction of current matters

While an inductor does not have any polarity, the direction of flow of current created from a phenomenon known as Kickback does matter. 

Kickback happens when the magnetic fields inside the coil collapse (instantly) causing very high voltages that range in the thousands to the tens of thousands.  

These high voltages can damage other sensitive components in the circuits such IC’s and transistors. 

The kickback phenomenon is going to happen regardless of which way an inductor is placed in a circuit, however, the current generated from kickback is just going to travel in the opposite direction.

A circuit designer’s main concern is which way this current is going to travel. They will need to design the circuit so that the kickback current does not damage other components.

Fly-back Diodes are used to protect components from this excessive current. 

Markings on an Inductor

But what about markings on an Inductor?

Many inductors come marked with a dot on one side. Does this mean this side is the positive side?

No, the dot is placed there by manufacturers to let you know which side of the inductor winding of the coil started. 

Again, this does not indicate the polarity of the inductor. 

Manufacturers also include information in the datasheet letting you know which way the coil is wound.

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They are a switch mechanism that consists of a spring that returns the button back to its original position after being pressed.

Push buttons come in a variety of shapes and sizes to suit the application it will be used for that can include things like Telephones, Arcade Machines, Calculators etc

But, do push buttons have polarity? A standard push button does not have polarity. A standard push button has two terminals which do not have polarity, so the direction it is wired does not matter. 

However, a note needs to be made that some push buttons contain Light Emitting Diodes (LED’s) which do have polarity. 

Push button with LED’s will have four terminals. Two of these terminals will be for the LED and will need to be wired the right way due to it having polarity.

What is polarity?

Before diving into why a standard push button does not have polarity, let us get a better understanding of what polarity is.

Without going into too much detail, polarity refers to components having two poles; Positive and Negative. 

You might be familiar with a battery and its Positive and Negative terminals. Due to this it is said to be polarised. 

A chemical reaction inside the battery causes a charge (known as current) to flow from the positive terminal of the battery to the negative terminal. 

Much like a battery, many other components have a polarity due to the way they are constructed. 

It is important to remember that the way a component is constructed largely determines whether it has polarity or not. 

They also have  Positive and Negative terminals. 

Below are common components that have polarity:

• Diodes 
• Light Emitting Diodes
• Electrolytic Capacitors
• Integrated Circuits
• Transistors
• MOSFETs
• Voltage Regulators

Let’s take a look at a Light Emitting Diode (LED) in a circuit with a battery. Below is the circuit symbol of an LED. As you can see, it has a Positive and Negative terminal denoted by the positive and negative symbols respectively. 

In the diagrams below we have connected the LED to a battery.

In diagram A, the LED is wired incorrectly. It’s positive terminal is connected to the battery’s negative terminal, while its negative terminal is connected to the battery’s positive terminal. 

In this instance current will not be able to flow and power through the LED, and there is even a chance of damaging the LED.

In diagram B, the LED is wired correctly. The positive and negative terminals of the battery and LED are wire together. Now, current can flow and power the LED. 

Why a standard push button does not have polarity

Now that we understand polarity a little better, we can take a look at the standard push button and see how it does not have polarity. 

As mentioned earlier, polarity comes down to the construction of components. So let’s take a closer look at the standard push button.

The circuit symbol of a push button can be seen below.

A push button is constructed using mechanical parts which have the ability to conduct electrical current (which can be any metal that is good at conducting electricity). 

It does not have any materials that give it a polarity. It is simply made of materials that allow current to flow when the button is pushed. 

Think of it as a  piece of wire. Current will pass through that wire no matter how it is wired as it does not have polarity. 

Also, inside the push button is a spring which returns the button to its original position after being pressed. 

The button itself is made of a non-conducting material such as plastic to protect the user from any currents when they push the button.

Certain type of push button that have polarity

Now, I have discussed how a standard push button does not have polarity. However, there is a certain type of push button that does have polarity and must be wired correctly.

This type of push button contains a Light Emitting Diode (LED) inside it which illuminates when the button is pressed. Below is the circuit symbol for a push button with an in-built LED.

As you can see, this type of push button has four terminals, two for the push button itself, and two for the LED. 

While it does not matter which two terminals of the push button are wired to the negative or positive terminals of the battery, it does matter how you wire the two terminals of the LED to the battery terminals as it has a polarity. 

A common application where these types of push buttons are used, and you might be familiar with is in Arcade machines. 

What is the main purpose of a push button?

A normal toggle switch in an electrical/electronic circuit provides a way of powering a circuit with more permanence.This means when the switch is closed it remains in that state until you reverse its position.

However, a push button is quite different compared to a normal toggle switch. A push button only allows current to pass when it is being pressed. When the push button is released, the circuit is broken and therefore no current can pass.

That is why push buttons are commonly referred to as Momentary switches, because they only provide power to a circuit ‘momentarily’. 

So, their main purpose is to be able to provide power to a circuit only when their button is being pushed. Due to this, the push button sees itself being used in a variety of applications.

A common application of where you would use a push button and not a toggle switch is a Drill. The main reason you would use a push button and not a toggle switch, is because of safety reasons. 

Since the drill is a dangerous piece of equipment, you only want to operate it when you are pressing the push button. As soon as you release the push button you want the drill to stop. Using a toggle switch might be hazardous and cause some issues.

Also, push buttons can be used as inputs to microcontrollers which can read a button press as an external event.

Applications where a push button can be used

As the main purpose of a push button is to provide momentary power to a circuit, this opens up many possibilities and applications where a push button can be used.

Below are some of the many applications where a push button can be used:

• Car Ignition
• Mobile / Telephone keypads
• Laptop / PC keyboards 
• Arcade machines
• Calculators
• Elevators
• Kitchen Appliances
• Emergency stop buttons
• Guitar Pedals
• Gaming controllers

Is there an alternative to using a push button?

So, the main purpose of a push button is to provide monetary power to a circuit when it is pressed.

Is there an alternative type of switch that can provide the same kind of functionality as a push button?

While the push button is the standard go to when a momentary switch is required, there are other certain switches that provide a similar momentary type function like the push button. These include Micro switches, reed switches and capacitive touch sensors.

As long as they are momentary by nature they can be used as an alternative to a standard push button.

How to determine whether a push button has polarity or not

If you have a push button lying around, or have purchased one and are not sure if the push has a polarity or not, do not fear, you will be able to tell if the push has polarity or not by looking at its terminals. 

If the push button that you have has two terminals, this is an indication that it does not contain a LED and therefore will not have any polarity. You can wire the push button either way.

However, if the push button has four terminals, this indicates it might possibly have a LED and therefore has polarity. 

The LED terminals of the push button will be marked with a + and – sign for its positive and negative terminals respectively. 

But, there are push buttons that do have four terminals and no LED. These push buttons will not have any positive or negative markings. 

Another way of finding out if a push button has polarity, is to look at its datasheet. The datasheet will be provided on the website of the manufacturer who created the push button. 

Benefits of a push button not having polarity

There are many benefits of a push button not having polarity. 

For instance, you do not have to constantly worry about which terminals have to be wired to positive or negative, constantly having to consult the datasheet. 

If you do happen to wire the push button the wrong way, you are not going to damage it as it does not have a polarity. 

This all saves time in the long run!

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